"It's fantastic to have completed half the journey to our next flyby; that flyby will set the record for the most distant world ever explored in the history of civilisation," said Alan Stern, New Horizons principal investigator from the Southwest Research Institute in Boulder, Colorado, in a NASA statement.

The spacecraft will be in hibernation mode later this week, and will be flying dark through the halfway timing marker to MU69.

"In addition to MU69, we plan to study more than two-dozen other KBOs in the distance and measure the charged particle and dust environment all the way across the Kuiper Belt," Weaver added.

Presently, the New Horizons spacecraft is at a distance of 5.7 billion km ( 3.5 billion miles) from Earth. Radio signals sent to the spacecraft by the research team on Earth take 5 hours and 20 minutes to reach the craft, even at the speed of light.

What is the Kuiper Belt?

The Kuiper Belt is a band of rock and other natural space debris that forms a circumstellar disc around our solar system. While the belt comprises a large number of asteroids it is also home to billions of rocks containing volatiles like water and methane, held over from the Solar System's formation. The KB is also home to Pluto, Haumea, and Makemake.